iOS Simulators not showing up in 3.4.0 when attempting to build

Hi guys,

I'm tearing my hair out here tying to get Studio 3.4.0 to pick up my iOS 8 (or iOS 7) simulators.

I've deleted and reinstalled both Studio and XCode 6.0.1 and the projects that were launching previously no longer let me open these apps in the simulator.

This is the console error I get.

[ERROR] :  Invalid "--device-id" value "iPhone Retina (4 inch)"

I've tried loads of different devices, none of which work. Interestingly, the previous devices that were in the list that referenced iOS 8 are missing as well.

Anyone know what I can do to remedy this?

I am using OSX Yosemite GM2 if that makes a difference!

Many thanks

Simon